WIMRC Scoping

1
WIMRC Scoping Feasibility Projects Final Review
Presentations

• 24th October 2006
• Cold Metal Transfer (CMT) Joining of Steel to
  Aluminium FEAP01
• Presented by Dr Ian Tuersley, Craig Pickin

2
Original Objectives
Cold Metal Transfer (CMT) Welding CMT is a new
MIG welding process offering controlled material
transfer with low thermal input 30 less heat
than conventional welding processes. Steel /
Aluminium joints are possible with this process
as low thermal input avoids brittle inter
metallic phases in the joint (typically Fe
dissolving in the Al). Al is welded, Steel is
brazed.

• Define critical factors for joining these
  materials using microstructural analysis.
• Conduct initial corrosion tests.
• Forge collaborative links Industrial and
  Academic.
• Journal Publications.
• Write/submit funding proposal.

3
AchievementsObjective 1 Determination of
Process Window.

• Simple process window defined based upon
  mechanical testing.
• Too much thermal input results in brittle
  cracking of bead and inadequate joint strength.
  This suggests that large quantities of Fe have
  dissolved into the Al (FeAl3 / Fe2Al5
  inclusions).
• Too little thermal input results in inadequate
  fusion of the aluminium parent material resulting
  in tear out of the aluminium parent from the
  bead.
• Optimised joints show failure in the aluminium
  parent material when tested in tension. Result
  values are similar to bulk aluminium welded
  joints this being approx 60 of the strength of
  the parent material.

4
AchievementsObjective 1 Microstructural
Characterisation of Joint Interface.

• Joint interface highlights an area rich in Fe
  and Al (point 3) suggesting that this is the
  strengthening mechanism.

Processing option All elements analyzed
(Normalised) Spectrum Al Si Fe Total 1 54.
38 43.51 2.10 100.00 2 77.32 12.86 9.82 100.00 3
61.10 5.08 33.82 100.00 4 97.30 1.97 0.72 100.00

5
AchievementsObjective 1 Microstructural
Characterisation of Bead Edges.

• Included zinc is evident around the edges of the
  weld bead indicating that protective coverage of
  the steel sheet is retained after joining.

6
AchievementsObjective 2 Initial Corrosion
Testing.

• Potentiodynamic polarization curves have been
  collected although analysis based upon process
  window yet to be conducted - i.e. what is the
  influence of heat wrt to microstructural changes
  and zinc burn off from steel plate.

7
AchievementsObjective 3 Collaborative Links.

• Industrial partners identified are predominantly
  automotive and associated supply chain these
  being
• CovPress (presswork and fabrication)
• TPS-Fronius (welding supply and development)
• JLR (automotive)
• Widney (aluminium window frames for automotive)
• Corus (materials supply)
• STADCO (fabrication)
• An academic partnership has been established with
  Birmingham University (Department of Metallurgy
  and Materials) leading to a joint proposal
  submission.
• Academic links have been established with Dr.
  Rajan Ambat at DTU (Technical University of
  Denmark) expert in the corrosion analyses of
  these systems.

8
AchievementsObjective 4 Publications.

• Arising out of the literature review, a paper
  Welding of Aluminium Alloy using the Cold Metal
  Transfer (CMT) Process is currently in print
  with the journal Science and Technology of
  Welding and Joining
• The initial microstructural and corrosion results
  are currently being written up as a further
  publication.

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AchievementsObjective 5 Full Proposal.

• A reactive bid to the EPSRC, The
  Characterisation and Optimisation of Cold Metal
  Transfer (CMT) Joining of Steel and Aluminium
  Sheet Materials, F387108 is in the final stages
  of preparation
• A joint proposal with Birmingham University
  Department of Metallurgy and Materials, (Dr.
  Alison Davenport and Prof. Ian Jones).
• A three-year programme of work involving the
  integration of processing, mechanical testing,
  microstructural and electrochemical studies to
  determine optimal parameters with full process
  characterisation.
• WMG component of bid approximately 0.5M
• Work Plan

10
What Was Not Achieved Why?

• All five stated project objectives have been
  achieved.

11
Impact On WIMRC Industry

• Literature survey has indicated that previous
  research has been conducted in this area using
  predominantly laser and friction stir welding.
  However control over intermetallic phases has not
  been possible with the result that these
  processes are not production viable.
• WIMRC results indicate that many of the
  identified problems associated with joining these
  materials have been reduced or even eradicated
  when using CMT.
• To date this is the only independent research
  world wide using CMT for this method of joining.

12
What Next?

• Submission of full proposal to EPSRC (currently
  only awaiting letters of support from industrial
  collaborators).
• Further journal publications reporting initial
  microstructural and electrochemical analyses.

13
Concluding Remarks

• The WIMRC Feasibility funding has enabled the
  background investigations to be carried out and
  collaborative links to be established, enabling a
  proposal for a full programme of research to be
  written.
• Proof reading feedback of the proposal suggests
  that it presents an interesting, coherent and
  rigorous programme of research with good links
  and collaborations.